Refrigerating compressors



March 14, 1967 cu 3,309,009

0 REFRIGERATING COMPRESSORS Filed April 28, 1965 4 Sheets-Sheet 1 FIG! .mwrrw 7 77 W D a March 14, 1967 R. CULK 3,309,009

' REFRIGERATING COMPRESSORS Filed April 28, 1965 4 Sheets-Sheet 2 March14, 1967 R. CULK 3,309,009

REFRIGERATING COMPRESSORS Filed April 28, 1965 4 Sheets-Sheet 5 March14, 1967 R. CULK 3,309,009

REFRIGERATING COMPRESSORS Filed April 28, 1965 4 Sheets-Sheet LL FIG. 4

United States Patent Ofiiice 3,309,009 Patented Mar. 14, 1967.

3,309,009 REFRIGERATING COMPRESSORS Raimund Culk, Varenaweg 1, Graz XI,Styria, Austria Filed Apr. 28, 1965, Ser. No. 451,465 Claims priority,application Austria, May 12, 1964, A 41,346/64 6 Claims. (Cl. 230-58)The invention relates to a refrigerating compressor with preferablyvertically flange-mounted electric motor the rotor of which is locatedin overhang on the compressor shaft and is separated from its stator bya hood consisting of a thin-walled cylindrical part of chrome nickelsteel surrounding the rotor with very little clearance, and a lid-shapedpart forming the hood top, as well as a flange-like part forming thehood edge, wherein the hood and the stator housing are mounted via asupporting ring on the compressor housing.

For the perfect operation of electric motors with separating hoods it isessential that the cylindrical hood part between the rotor and thestator of these motors should be as thin as possible, because theefliciency and the cos value decline with increasing air gap whilst athicker cylindrical hood portion causes higher eddy current losses if itis made from conducting material. In addition, the cylindrical hoodportion must be sufliciently strong to resist the often high internaland external pressures. These factors have hitherto limited the size ofmotors equipped with such separating hoods.

The present invention has the object of enabling the separating hoodalso for larger electric motors'to be made economically whilstmaintaining its resistance to high internal and external pressures and ahigh power factor.

There are already known electric motors for driving refrigeratingcompressors which are made in several parts and wherein both thethin-walled cylindrical portion within the zone of the rotor orstatorparcel and the lidshaped portion forming the top of the hood are madefrom chrome-nickel steel. On the other hand, the thicker shell partforming the edge of the hood is made of ordinary steel and mounteddirectly in a centering face of the supporting ring on which is alsomounted centrally the stator housing. The cylindrical part and thelid-shaped portion of the hood, forming the top are drawn on a pressfrom a circular blank of chrome-nickel steel sheet, whereby, althoughthe hood is given a high degree of rigidity, waste occurs already whenstamping the circular blanks from rectangular steel plates. In addition,when drawing the hood, the material is often weakened and theseweaknesses do not become apparent until the hood has been finished.Another drawback of these known designs of refrigerating compressors isthat the supporting ring is a separate component, since the hithertoused iron rings had to be fully machined and connected by welding orsoldering to the reinforced part forming the edge of the hood. Moreover,at this joint which must be absolutely gastight, leaks may occur whichcause expensive repairs and interruptions in the manufacture. Especiallywhere large numbers are produced, the production costs of the supportingrings, the machining time and the production of thejoints are ofrelevant importance.

According to another known construction, also proposed in connectionwith refrigerating compressors, the production costs are lowered in thatonly the thin-walled cylindrical part of the hood is a stainless steel,whilst the lid-shaped portion forming the hood top and the flangedreinforced part forming the hood edge are of non-magnetic material witha very high electric resistance. The thin-walled cylindrical hoodportion is made from a suitably cut sheet metal member which is bent toform a cylinder and welded along the edges in overlap. To enable thisthin-walled cylinder to withstand the internal and external pressures, asupporting cylinder of magnetically conducting material is arrangedtherein, having the shape of a hollow body urging the thin-walledcylindrical part against the inner periphery of the stator parcel.However, the manufacture of this supporting cylinder,

' consisting of alternating laminated toothed heads and longitudinalinsulating pieces, is very expensive and requires a speciallyconstructed stator parcel so that stators of conventional electricmotors cannot be used. Moreover, the reinforced part vforming the hoodedge is not made of sheet metal but from a metal ring which must befully machined which is difficult from the viewpoint of rationalproduction. Also, the hood is not fitted to the compressor housing by asupporting ring, but directly by a screwed joint, causing misalignmentsbetween rotor and hood.

According to the invention, these drawbacks may be avoided in that thethin-walled cylindrical part has at its edge connected with thelid-shaped part a diameter which I is smaller than it inner diameter,and the flange-like reinforced part of the hood is formed integrallywith the supporting ring and produced by drawing from sheet metal. 1

According to a further feature of the invention the lid-side end of thecylindrical hood portion is rounded off towards the longitudinal axis ofthe hood and connected directly with the edge of the lid-shaped part ofthe hood, e.g., by welding or soldering, on outer edge zone of thelid-shaped hood portion, which may be equipped with a shoulder thatrests against the inner surface of the rounded end of the cylindricalhood portion,

wherein the edge of the rounded hood end is connected by welding orsoldering with the other surface or with the shoulder of the lid-shapedhood portion.

This rounding off of the lid-side end of the cylindrical hood portionproduces a high degree of rigidity of the cylindrical portion so thatcollapsing or bulging under high pressures is avoided even withthin-walled construction of the hood. This rounding off can be producedby means of a rolling tool which is cheap and raises the productioncosts only negligibly. Moreover, in order to lower the production costsyet further, both the flanged, reinforced hood portion and thesupporting ring are made of one piece of sheet metal by drawing. To thisend, suitable blanks are cut, for example from 4 mm. steel plate, thenecessary centre recess is stamped out, and the prepared blanks arepressed on a drawing press into the required shape and finally equippedwith the necessary mounting holes or the like.

According to a further feature of the invention, the flanged, reinforcedpart of the hood may have in its outer wall portion a dish-shaped recessand/or a rim. Also, this hood portion may be made in two parts whereinthe outer ring of the divided hood portion is arranged in overlap on theinner ring and these two are mounted together on the compressor housing.Preferably, the ring shaped outer part is equipped with two centeringlugs.

For producing a fully hermetic compressor construc tion, the outer edgeor rim of the flanged reinforced hood portion may be connected to asheet metal dish or tank surrounding the compressor housing.

The configuration of the reinforced part of the hood and of thesupporting ring results not only in a substantial reduction in costs,but also reduces the overall weight and thus the carriage andtransportation costs, whilst a high degree of strength and accuracy isachieved in spite of the cheaper sheet material, owing to the use of thedrawing techniques.

The invention will be further described, by way of example, withreference to the accompanying drawings, showing several embodimentsthereof, and in which:

FIG. 1 shows the separating'hood and the supporting ring in axialcross-section, viz., FIG. 1a and 1b showing further details of the hood;

FIGS. 2 and 3 show embodiments of the reinforced hood portion withvertical arrangement of the electric motor;

FIG. 4 shows an embodiment of the reinforced hood portion withhorizontal arrangement of the electric motor.

According to FIG. 1, the separating hood 1 consists of a thin-walledportion 1, a flanged reinforced portion 1 and lid-shaped portion 1". Thethin-walled hood part 1 is made of chrome-nickel steel, cut torectangular or similar shape, bent and soldered or welded at the edges21. In order to increase the rigidity, the lid-side end 4 of the part 1is drawn in by means of a rolling tool so as to create a rounded offportion, the edge diameter d of which is smaller than the inner diameterD of the cylindrical part 1. The rounded off end 4 of the cylindricalpart 1' is not machined and has its full wall thickness. On the otherhand as seen in FIG. 2 between the stator 11 and the rotor 10, thecylindrical part is as thin-walled as possible. The edge of thelid-shaped hood portion 1" is connected by welding or soldering with theedge of the rounded off portion 4 of the cylindrical hood part 1' eitherdirectly (FIG. 1) or as shown in FIGS. la and 1b, in which thelid-shaped hood portion 1" rests with its edge zone '5 against the innersurface of the rounded off hood end 4, the edge of the head end beingconnected by soldering or welding to the outer surface of the part 1".The lid-shaped part 1" may have a shoulder (FIG. 1b) to which the edgeof the rounded off hood end may be soldered or welded.

The flanged reinforced part 1" is formed integrally with a supportingring 20 and is made by suitable tools by using drawing techniques. Theouter edge zone, having the ring has either a dish-shaped recess 2 or arim 3. Both may be provided as shown on the right side in FIG. 1. Thisrecess 2 and/or rim 3 reinforces the part carrying the supporting ring20 of the portion 1" so that even comparatively thin sheets may be usedfor the manufacture thereof.

FIGS. 2 to 4 show the assembly of the separating hood 1 according to theinvention with piston compressors of various designs. FIG. 2 shows asingle piston compressor whose housing 15 is centered through a shaftbearing 18 on the reinforced hood part 1" and connected thereto byscrews 15. The outer edge of the recess 2 has holes 2 for the fixingscrews 13 for the stator housing 12, which is equipped with cooling ribs12' and carries the stator 11 Between the stator 11 and the rotormounted on the compressor shaft 9 is the thin-walled hood portion 1'.The stator and its windings are covered by a hood 19.

On the right side in FIG. 2 there is shown a divided reinforced hoodportion 1", consisting of an inner ring 7 and an outer ring 6, thelatter overlapping the inner ring 7 and mounted together therewith byscrews 15 on the compressor housing 15.

FIG. 3 shows a twin bearing two-cylinder refrigerating compressor, onwhose separating hood 1 on the outer edge of the flanged reinforced hoodpart 1" is mounted a sheet metal dish 16 which fully encloses thecompressor housing. This sheet metal dish 16 may also be welded to theouter edge of the hood portion 1" so that the compressor is fullyhermetically and tightly enclosed in the vessel formed by the hood 1 andthe sheet metal dish 16. As may be seen from the right side of FIG. 3,the recess 2 in the hood portion 1" may also be downwardly directed,wherein the stator housing 12 fests through retaining lugs 17 or aretaining ring on the hood portion 1" or its supporting ring 20 and ismounted together therewith by screws 15 on the compressor housing 15. Inthe embodiment shown in 'FIG. 3, left side, screw nipples 14 are weldedto the outer edge zone of the hood portion 1 for mounting the statorhousing 12 into which may be screwed bolts 13 arranged between thecooling ribs 12'.

FIG. 4 shows a two-cylinder refrigerating compressor with horizontallyflange-mounted electric motor, whose rotor is mounted on the rotor shaft9 and separated from the stator 11 by a thin-walled cylindrical hubportion 1.

The shaft bearing 18 is mounted by screws 18 on the compressor housing15 whilst the separating hood 1 is centered on the end face 22 of theshaft bearing 18 and mounted by screws 15 on the compressor housing 15.In the embodiment of the reinforced hood portion 1" in FIG. 4, bottom,the same has a deep recess 2 with weldedon tongue-shaped lugs 8 formounting the stator housing 12. The lugs 8 may also be bent out of theupper rim of the recess 2. Also a divided construction of the reinforcedhood portion 1" is possible with horizontally flangemounted electricmotor, as shown in the upper part of FIG. 4. This requires that theouter ring 6 be equipped both with a centering lug 6' for the inner ring7 and with a centering lug 6" for the stator housing 12, because goodalignment of all parts can be guaranteed only in this way. This dividedconstruction is suitable especially for the use of commercial motorsbecause the bearing plates of these motors can be easily replaced by anouter ring 6 formed by a heavy casting.

The invention is not restricted to the embodiments hereinbefore shownand described. In particular, the flanged reinforced hood portion may bestiffened by other embossings and further elements, such as lugs, may beprovided on its outer edge for supporting or suspending therefrigerating compressor.

What I claim is:

1. A refrigerating unit containing a compressor having a housing and anelectric motor drivingly coupled to said compressor, said electric motorincluding a stator, a stator housing and a rotor, the improvementcomprising a hood composed of three joined sections; the first sectionbeing a thin-walled cylindrical part made of stainless steel interposedbetween said stator and said rotor and having at one end an inwardlyconverging annular portion defining an aperture of smaller diameter thanthe diameter of the cylinder; the second section being a lid joined tosaid first section to close said aperture; the third section being adrawn annular reinforcing member joined tothe other end of said firstsection and by which the hood and stator housing mounted on thecompressor housing by securing means.

2. A refrigerating unit according to claim 1 wherein the said firstsection is metallurgically joined to the said second section.

3. A refrigerating unit according to said third section is formed withan integral outwardly extending flange portion.

4. A refrigerating unit according to claim 3 wherein said flange portionis shaped so as to define an annular recess. a

5. A refrigerating unit according to claim 1, wherein the said thirdsection is formed of inner and outer reinforcing member portionsarranged to overlap, and means are provided for securing both of saidportions at their overlap to said compressor housing, the innerreinforcing member portions being joined to said first section and theouter portion being secured to said stator housing.

claim 1, wherein 6. A refrigerating unit according to claim 5, wherein2,827,855 3/1958 Rankin 103-87 the said outer poition'carries a firstcentering lug for 00- 911 549 11 1959 Culk 310 35 operation with theinner portion and a second centering lug for co-operation with the saidstator housing. FOREIGN TS 5 References Cited by the Examiner 9573592/1950 France UNITED STATES PATENTS ROBERT M. WALKER, Primary Examiner.

1,233,569 7/1917 Graemiger 310-86

1. A REFRIGERATING UNIT CONTAINING A COMPRESSOR HAVING A HOUSING AND ANELECTRIC MOTOR DRIVINGLY COUPLED TO SAID COMPRESSOR, SAID ELECTRIC MOTORINCLUDING A STATOR, A STATOR HOUSING AND A ROTOR, THE IMPROVEMENTCOMPRISING A HOOD COMPOSED OF THREE JOINED SECTIONS; THE FIRST SECTIONBEING A THIN-WALLED CYLINDRICAL PART MADE OF STAINLESS STEEL INTERPOSEDBETWEEN SAID STATOR AND SAID ROTOR AND HAVING AT ONE END AN INWARDLYCONVERGING ANNULAR PORTION DEFINING AN APERTURE OF SMALLER DIAMETER THANTHE DIAMETER OF THE CYLINDER; THE SECOND SECTION BEING A LID JOINED TOSAID